Connector for use in capacitive graded splices

ABSTRACT

Electrostatic connector means, for joining the central conductor connector in a cable splice with an equipotential ring surrounding a non-conducting supporting sleeve, including an annular conductive member attached to the conductor connector and spring biased plungers connected to the ring and extending inwardly through apertures in the sleeve into contact with the annular conductive member.

United States, Patent [1 1 Kat-z et alfv [5 1 CONNECTOR FOR use IN CAPACITIVE GRADED SPLICES [75] Inventors: Carlos Katz, Spring Valley; Felipe Garcia; Elsayed Allam, both of New City, all of NY.

[73] Assignee: The United States of Americans represented by the Secretary of the Interior, Washington, DC

[22] Filed: Nov. 7, 1973 [21] Appl. No.: 413,706

[52] U.S. Cl. 174/73 R, 174/21 R, 339/254 R [51] Int. Cl H02g 15/08 [58] Field Of Search 174/21 R, 21 18, 21C,

174/22 R, 22 C, 73 R, 73 SC, 142, 143; 317/260, 339/254 R, 254 M, 255 R [56] References Cited' UNITED STATES PATENTS 8/1935 Atkinson 174/73 R OX 7 Primary Examiner-Laramie E. Askin Attorney, Agent, or Firm-Davis, Hoxie, Faithfull &

Hapgood [57] ABSTRACT Electrostatic connector means, for joining the central conductor connector in a cable splice with an equipotential ring surrounding a non-conducting supporting sleeve, including an annular conductive member attached to the conductor connector and spring biased plungers connected to the ring and extending inwardly through apertures in the sleeve into contact with the annular conductive member.

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CONNECTOR FOR-USE IN CAPACITIVE GRADED SPLICES This invention resulted from work done under Contract No. 14-0l001-l557 with the Department of the Interior.

The present invention relates to prefabricated capacitive graded'cable splices of the type disclosed in pending U.S. Pat. application Ser. No. 397,113, filed Sept. 13, 1973 and assigned to Phelps Dodge Industries, Inc. That application discloses a reliable, readily installed, prefabricatedv cable splice device that reduces field installation time and eliminates the need to form stress relief cones at the cable joint.

One structural feature of that'invention. is a radially oriented leaf spring electrostatic connector which joins the centrally disposed conductor connector with a surrounding equipotential shielding ring. When the prefabricated splice device there disclosed is slipped into place, the outer ends of the leaf springs fall into narrow longitudinally oriented slots spaced around the perimeter of an insulating sleeve to make contact with the surrounding shielding ring. In practice, it has been found that exact placement of the inner ends of the leaf springs on the'conductor connector is difficult, with the result that the outer ends of the leaf springs do not always fall into place in the slots and make proper connection. Improper connection causes high voltage discharges and ultimately the breakdown of the system.

It is an object of the present invention to provide an improved electrostatic connector that seats more reliably into place when the cable splice is assembled.

It is a further object of the present invention to'providean electrostatic connector that physically strengthens the cable splice against radially directed stress.

I .Attempts have been made to accomplish these objects using outwardly directed spring biased'electrically conductive plungers mounted in some fashion on the.

centrally disposed conductor connector. However, such a system does not insure any more reliable seating of the plungers into the. apertures in the supporting sleeve than does the systemusing leaf springs. The only way to insure the achievement of proper contact between the-outwardly directed plungers and the shielding ring is to splitthe insulating supporting sleeve into two parts and install a grooved metal ring in the gap between them. But such a modification substantially impairs the strength of the sleeve assembly, an impairment which unacceptably weakens the longitudinal V strength of the splice.

Briefly, the present invention involves replacing the leaf spring connector previously used with a connector utilizing spring biased plungers mounted in the equipotential shielding ring and extending inward through small slots in the supporting sleeve to cooperate witha rigid annular conductive member located between the conductor connector and the supporting sleeve. The system of the invention accomplishes the objects stated above without weakening the rigid supporting sleeve. The splice of the present invention also has improved longitudinal stability, making it more resistant to stress caused by heat expansion of the cable. Further, the rigid annular member used in the device of the present invention aids in dissipating heat from the conductor connector.

The invention is illustrated in the accompanying drawings in which:

FIG. 1 is a side view of a prefabricated capacitive cable splice device disclosed in U.S. Pat. application Ser. No. 397,1l3, using the leaf spring connector;

FIG. 2a is a detail of a similar splice device using the connector of the present invention;

FIG. 2b is a further detail of the splice device shown in FIG. 2a, showing one construction of the plunger assembly;

FIG. 2c is a further detail showing another construction of the plunger assembly;

FIG. 2d is an end view of the annular member; and

FIG. 3 is an end view of another embodiment of the annular member.

, 12 are a pair of identical capacitive graded-sections 16 and 18, respectively. The capacitors at the ends 20 and 22 of the capacitive graded sections 16 and 18 adjacent the shielding ring 14 are electrically connected to it, and the capacitors at the remote ends 15 and 17 of the capacitive graded sections 16 and 18 are electrically connected to a metallic splice shield 26. Cable insulation shields 19 and 21 may be electrically connected to the metallic splice shield 26, e.g., by metallic tape 23 and 33, respectively. The shielding ring 14 and capacitive graded sections 16 and 18 are surrounded by a cylindrical insulating member 24, e.g., of electrical grade cellulose paper, and the metallic shield 26.

The rigid supporting sleeve 12 is formed from insulating materials, e.g., phenolics, epoxies or other rigid synthetic materials. The sleeve 12 has a plurality of longi: tudinally oriented slots or apertures 25 spaced around its perimetenEach aperture receives one end 29 of a leaf spring. type electrostatic connector 28 for contact with the electrostatic shielding ring 14. The shielding ring 14 serves as an equipotential element to which the high voltage side of the graded capacitors are connected. The other end 27 of the electrostatic connector 28 contacts a conductor connector 30 which. electrically joins the central conductors 32 and 34. Other parts of the cable splice device visible in FIG. 1 include the main cable insulation 36 and 38 and optional oil impregnated paper insulating tubes 50 and 52. j

The longitudinal and radial distribution of voltage stress is achieved by utilizing printed circuit or foil laininated capacitors of the type disclosed in the aforementioned U.S. Pat. application Ser. No. 397,113, filed Sept. 1'3, 1973. 1

In the splice device of the present invention, shown in FIG. 2a, spring type connector 28 is removed and an electrical path between conductor connector 30 and the equipotential shielding ring 14 is made instead by rigid annular member 600 attached to the conductor connector 30 and a plurality of inwardly directed spring loaded plunger assemblies 500 each of which is attached to the shielding ring and extends inward through small circular slots 25 in the supporting sleeve.

Each plunger assembly 500, a typical one of which is shown in more detail in FIG. 2b, includes an electrically conducting plunger casing 510 fixed within shieldingring 14 with its innermost portion adjacent an apertur 3 25 in supporting sleeve 12, a plunger 520 protruding radially through aperture 25 toward the center of the cable from plunger casing 510, a plunger mount 540 screwed into the base of plunger 520 and having an enlarged rear portion 550 adapted to contact the rear of casing 510 when the inward protrusion of plunger 520 is a maximum, and a compressed spring 560 sandwiched between the rear end of casing 510 and the enlarged base portion of plunger 520, to urge plunger 520 inward.

Annular conductive member 600, having in its peripheral rim an annular groove 620 located between two humps 640 and 660, may be prefabricated as a part of conductor connector 30 (see FIG. 2d). During assembly of the cable in the field as described in U.S. Pat. application Ser. No. 397,113, one of humps 640 and 660 will contact the normally protruding nose of plunger 520 and force the plunger back into casing 510. As the assembly operation reaches completion, the contact point between plunger 520 and the hump will move beyond the point of the hump, and the plunger will then move back out and come to rest in groove 620 located between humps 640 and 660. Electrical contact is thereby made between conductor connector 30 and shielding ring 14.

At the same time, annular conductive member 600 can be made as rigid as desired, and its dimensions can be chosen so that it completely fills the space between conductor connector 30 and the inner surface of sleeve 12. In this way, the present invention provides a splice having great strength against radially and longitudinally directed stress and improved thermal dissipation propertles.

As is shown in FIG. 2b, if a plunger mount 540 is employed, assembly 500 should be countersunk below the outer surface of shielding ring 14 a sufficient distance so that when plunger 520 is forced back into casing 510 by one of humps 640 and 660, the enlarged rear portion 550 of the plunger mount is not pressed against insulating member 24.

Another embodiment of the invention is shown in FIG. 2c. This embodiment employs a bore in shielding ring 14 instead of a separate casing for the plunger 500. As before, plunger 720 is shaped with a cylindrical rear portion and a tapered front portion, though the enlarged base portion of the previous embodiment may be eliminated. The plunger is urged inward toward the center of the cable splice device by compressed spring 740, held in place within the bore by plug 760 which may be screwed into the rear of the bore from the outer surface of shielding ring 14. Inward movement of the plunger is limited by a constriction 780 formed in the aperture 25 through sleeve 12. The plunger in this embodiment cooperates with the annular member 600 in the same manner as that described for the previous embodiment.

Another embodiment of the annular conductive member 600 is shown in FIG. 3. This embodiment includes openings 670 in the member, to allow adequate circulation of the liquid dielectric (oil) 48 (see FIG. 1) within the splice device 10.

It should be understood that the invention is not confined to the particular embodiments illustrated. For example, the cross-sectional shape of the plunger and the chamber in which it moves could be other than circular, the plunger mount used in the embodiment of FIG. 2b could be eliminated if not needed for stability, etc. In addition, the annular member need not be of one piece construction and may be conductive only in places. These and other modifications may be made in the present invention without departing from the spirit and scope thereof as described in the specification and defined in the appended claims.

What is claimed is:

1. In a cable splice device for joining the ends of two cables, said splice having a non-conducting rigid supporting sleeve including at least one aperture radially therethrough, an equipotential shielding ring surrounding said supporting sleeve, and a conductor connector encompassed by the ring for electrically connecting the conductors of the two cables to be joined: the improvement comprising electrostatic connector means for providing electrical connection between said conductor connector and said equipotential shielding ring having an annular conductive member attached to and extending radially of said conductor connector and having a peripheral rim proximate to said supporting sleeve and coaxial with said conductor connector, said rim having an annular groove, and at least one spring biased conductive plunger extending radially inwardly from said shielding ring through said aperture in said supporting sleeve, said plunger engaging said groove.

2. The cable splice device of claim 1 wherein said annular conductive member includes at least one opening therethrough for the passage of liquid dielectric.

3. The cable splice device of claim 1 wherein the inward movement of each of said plungers is limited by a constriction in said aperture.

4. The cable splice device of claim 1 wherein each of said plungers is located in a bore extending through said shielding ring. 

1. In a cable splice device for joining the ends of two cables, said splice having a non-conducting rigid supporting sleeve including at least one aperture radially therethrough, an equipotential shielding ring surrounding said supporting sleeve, and a conductor connector encompassed by the rIng for electrically connecting the conductors of the two cables to be joined: the improvement comprising electrostatic connector means for providing electrical connection between said conductor connector and said equipotential shielding ring having an annular conductive member attached to and extending radially of said conductor connector and having a peripheral rim proximate to said supporting sleeve and coaxial with said conductor connector, said rim having an annular groove, and at least one spring biased conductive plunger extending radially inwardly from said shielding ring through said aperture in said supporting sleeve, said plunger engaging said groove.
 2. The cable splice device of claim 1 wherein said annular conductive member includes at least one opening therethrough for the passage of liquid dielectric.
 3. The cable splice device of claim 1 wherein the inward movement of each of said plungers is limited by a constriction in said aperture.
 4. The cable splice device of claim 1 wherein each of said plungers is located in a bore extending through said shielding ring. 